Intraoperative probes that are guided by radiolabeled tracers increase the specificity of tissue biopsies, enable minimal-access incisions, reduce inpatient hospital utilization, and contribute to improved patient recovery. Intraoperative probes have been used in the treatment of cutaneous melanoma, squanious cell carcinoma, breast carcinoma, thyroid tumors, and parathyroid adenoma. At present, most such probes on the market are non-imaging, and provide no ancillary information of surveyed areas, such as clear delineations of malignant tissues. These probes are usually gamma-sensitive, and are used in conjunction with radiopharmaceuticals such as 18FDG, 99mTc, 1311, HIIN or 1251. One such probe, based on a CdTe sensor, has been supplied on an OEM basis to U.S. Surgical and sold directly under the brand name Navigator™.
The major drawback of existing gamma probes is their inability to distinguish between the signal from the tissue directly in front of the face of the probe head and the background resulting from surrounding tissues. Although they allow the surgeon to locate the approximate area of a tumor, they provide no delineation of the tumor site or tumor bed. This is an important issue, since the excision of all tumor tissue and minimal healthy tissue is important for the recovery, health and even survival of the patient.
An alternative approach in the design of surgical probes with higher spatial accuracy is to make the detector selectively sensitive to short-range radiation, such as beta rays. 18F-FDG, the FDA-approved widely used radiotracer for oncology, is both a beta and gamma emitter. Detection mechanisms can be implemented in a hardware-software imager design that will effectively measure gammas in order to navigate to a tumor site, and then subtract the gamma background, allowing real-time beta imaging with high contrast and high signal-to-noise ratio (SNR). Such a mechanism would be particularly effective when the probe is used near organs with high uptakes of the radiotracer, such as the bladder, heart, or brain, and can therefore generate background that prevails over the signal.
It would therefore be useful to develop a tool that surgeons can use to navigate to tumor sites and delineate the tumor site from surrounding tissue. Such a device can be made in a compact form, making it easy to use during surgery.